The clinical core of the RADP is a mechanism for prospective enrollment of patients with clinical criteria for probable Alzheimer's disease for post-mortem donation of brain samples; prospective enrollment of normal controls for post-mortem brain samples; assessing retrospectively the clinical histories of demented subjects whose brains are donated post-mortem for research study and making the diagnosis of dementia of the Alzheimer type; and assessing retrospectively the clinical histories of nondemented subjects whose brains are obtained as normal controls. The aim is to accrue a total of approximately 75 brains of patients with clinical and pathologic criteria for Alzheimer's disease, and approximately 45 brains from control subjects without clinical or pathologic criteria of any dementia disorder comparable in age and sex to the patients.